This invention relates to an apparatus for supplying liquid such as liquid fuel such as gasoline, alcohol or the like, or lubrication oil, etc. to the interior of an intake passage of an internal combustion engine.
There has been known apparatus of this kind in which a liquid chamber containing liquid such as gasoline or the like is provided at the side of an intake passage in an internal combustion engine, and the chamber is in communication with the intake passage through a delivery passage having a metering or throttle portion interposed therein, so that when there is generated a negative pressure in the intake passage, the liquid is sucked by the negative pressure into the intake passage through the delivery passage. It is usual with this type that the flow rate of the liquid introduced thereto will depend on the throttle size of the throttle portion, the difference between the pressures of the front side and the rear side thereof, and the viscosity of the liquid. Therefore, if the viscosity of the liquid is increased with lowering of a temperature, the flowing rate thereof tends to be decreased accordingly, but this is not desirable. Namely, in the case where the liquid is such fuel as gasoline, alcohol or the like, for instance, the starting characteristic of the engine, the driving property of the vehicle, the fuel consuming cost and others at the time of low temperature are liable to be unfavorable, and in the case where the liquid is lubrication oil, for instance, this may cause such an inconvenience that oil distribution becomes bad and the friction loss is increased.